The present invention is generally related to thermal management technology and, more particularly, is related to a system and method for cooling heat producing bodies or components.
Cooling of heat-producing bodies is a concern in many different technologies. Particularly, the rise in power dissipation levels of microprocessors, accompanied by a shrinking thermal budget has resulted in the need for new cooling solutions beyond the conventional thermal management techniques. Indeed, thermal management is a major challenge in the design and packaging of state-of-the-art integrated circuits in single-chip and multi-chip modules. The projected power dissipation levels of microprocessors are being reached well before their expected time. For example, while the International Technology Roadmap for Semiconductors, predicted a junction-ambient thermal resistance of 0.4xc2x0 C./W for cost performance computers by 2005, the current Intel Reference Heat Sink requirements are already at a case-to-ambient thermal resistance of 0.4xc2x0 C./W and expected to reduce further. International Technology Roadmap for Semiconductors, 1999 Edition, Semiconductors Industries Association Report, http://www.semichips.org/index2.htm. In addition, there is a rapidly growing need for new, more effective thermal management strategies to be used with small handheld devices, such as portable digital assistants (PDA""s), mobile phones, portable CD players, and similar consumer products.
Traditionally, the need for cooling microelectronic devices has been met by using forced convective cooling with or without heat sink devices. Forced convection is effected using fans which provide either global overall cooling or locally-based cooling. The use of fans to globally or locally cool a heated environment often results in electromagnetic interference and noise generated by the magnetic-based fan motor. Use of a fan also requires relatively large moving parts in order to have any success in cooling a heated body or microelectronic component. These large moving parts naturally require high power inputs.
In certain implementations, traditional fans are used in conjunction with heat sinks. However, in order to achieve the ever-increasing power dissipation levels with current fan-heat-sink combinations, designers are being forced to use copper heat sinks or aluminum heat sinks with copper inlays. Additionally, the increased thermal management requirements have also necessitated larger fans driving higher flow rates. Since the power dissipation requirements have necessitated placing fans directly on the heat sink in some instances, the associated noise levels due to the flow-structure interaction have become an issue. Also, while fans are capable of supplying ample volume flow rate, they may be hindered by long-term reliability. In addition, fan based cooling systems are relatively inefficient in terms of the heat removed at a given volume flow rate.
The need for thermal management has also been met in some instances, as in handhelds like portable digital assistants (xe2x80x9cPDAsxe2x80x9d), cell phones, etc. . . , by employing a strategy of spreading the heat produced by an integrated circuit, or other device through the use of heat sinks and spreaders. Then the heat generated is permitted to dissipate through the outer shell, or skin, of the device via unforced convection. While these approaches are common, they offer certain drawbacks that will be exacerbated as new products that produce even more heat are developed. The difficulty with the heat spreading strategy is simply that it is often ineffective at removing adequate quantities of heat. On the other hand, the amount of heat to be removed may overly heat the casing of the handheld device, which is not desirable from a consumer use standpoint. In addition, the heat sinks and spreaders involved can be bulky and costly.
Thus, a heretofore unaddressed need exists in the industry to address the aforementioned deficiencies and inadequacies.
Embodiments of the present invention provide a system and method for thermal management of heated bodies or environments. Briefly described, in architecture, one embodiment of the system, among others, can be implemented as a system for cooling. This first exemplary embodiment comprises a heated body, where heat is contained within this heated body. The first embodiment also comprises an ambient fluid adjacent to an exterior surface of the heated body. Walls forming a channel are disposed within an interior of the heated body. The heat contained in the heated body is moved into at least one of these channel walls. Finally, the first embodiment comprises a synthetic jet actuator adjacent to one of the channel walls. The synthetic jet actuator is positioned so as to direct a synthetic jet flow through the channel. As will be explained in more detail below, the operation of the synthetic jet actuator creates a flow consisting of the ambient fluid though the channel. This flow of ambient fluid cools the walls of the channel and thereby the heated body.
Although there are many other embodiments of the present invention, briefly described, in architecture, another embodiment of the system can be implemented as an integrated heat sink module. This integrated heat sink module includes a heat sink material and a heat generating body adjacent to the heat sink material. This second embodiment also comprises a synthetic jet actuator incorporated into the heat sink module such that the synthetic jet actuator creates a flow of an ambient fluid along a surface of the heat sink material. This flow of ambient fluid carries heat away from the heat sink material.
The present invention can also be viewed as providing methods for cooling. In this regard, one embodiment of such a method, among others, can be broadly summarized as a method for cooling a device having heat producing components. This method has the steps of: providing a device having an exterior surface, wherein the heat producing components are disposed within the exterior surface of the device; further providing that the device has a duct passing though an interior of the device and the duct is open to an external environment; directing a heat generated by the heat producing components into a wall of the duct; generating a synthetic jet steam in the duct; and entraining an ambient fluid from the external environment of the device such that the entrainment causes the ambient fluid to flow though the duct and cool the wall of the duct.
Other systems, methods, features, and advantages of the present invention will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims.